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Losing miles while plugged in

Discussion in 'Model S: Battery & Charging' started by invisik, Jul 10, 2014.

  1. invisik

    invisik Member

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    Hi all!

    This struck me as odd today--why does the car still lose miles while parked and plugged in? Shouldn't it be running from shore power (like how AC and heat does) ? I leave the car plugged in all day when I'm at my office on a 40amp J1772 and watch the miles drop in Visible Tesla.

    Further, then I don't get the motto: "a happy Tesla is a plugged-in Tesla".... what does that really mean? "a charged-once-a-day Tesla is a happy Tesla" ? The car doesn't seem to do much of anything beyond pre-cooling/heating the cabin with shore power after the main charging time is complete.

    Or is this part of the vampire drain concept?

    Thanks for any thoughts.....

    -m
    (I'm a relatively new owner, please be gentle) :)
     
  2. lloyds

    lloyds Member

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    What amperage / voltage is it running on? I usually wait for everything to boot up before I step out of the car to make sure it's charging. Perhaps it's a problem with the plug.
     
  3. Vger

    Vger Active Member

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    When the car is plugged in and just drawing a small mount of power to keep the electronics going, it still draws from the battery and loses some small amount of range. It will automatically check periodically and charge the car back up. I don't know what the threshold is, but other here may.
     
  4. iffatall

    iffatall Member

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    How much drop did you see?

    A couple of guesses I can make:
    1. The J1772 does not re-start supplying power automatically once it has been shut. Your car got fully charged, power draw stopped, J1772 turned off. A little vampire drain happened, but J1772 needs to be turned on again, manually.
    2. The car does not begin drawing power until the charge level drops below a certain level - may be a couple of miles of rated range - unless heating/cooling is actively going on.
     
  5. invisik

    invisik Member

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    40amp, 208v, about 20-22mph usually. When I plug it in it definitely charges, then stops at the charge limit like it is supposed to. Then the car sits there, with the cord still plugged in, all day slowing losing rated miles.

    If I manually initiate a charge cycle again (like unplug the J1772 and plug it back in), it will charge again to the charge limit. But then will continue to lose miles again...

    -m

    - - - Updated - - -


    Today I have lost 2 miles from 8am until 1pm.

    I'm guessing theory #1 is the most accurate... but I'd expand it to say it also happens at my home on the Tesla HPWC. For example, if I have the charge timer set for 1am, when I get in the car at 7am it is already down a few miles.

    It does not appear to keep the battery "topped off". I think that is the behavior I'm expecting as it is "plugged in".

    -m
     
  6. Btrflyl8e

    Btrflyl8e Active Member

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    As Vger stated, I believe it has to hit a threshhold before it restarts charging. I read on another thread that someone said it's not a miles threshhold, but a 24 hour "cycle". I have not confirmed either, but I think it is normal for the drop in range during the day, even though plugged in. Mine does it too, anyway! I just don't worry about it.
     
  7. rolosrevenge

    rolosrevenge Dr. EVS

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    It's a shame that the vampire loads can't bypass the battery and pull directly from the charger when plugged in.
     
  8. dsm363

    dsm363 Roadster + Sig Model S

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    You could always just drop to 12A or something low and charge on plug in.
     
  9. SeminoleFSU

    SeminoleFSU Member

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    #9 SeminoleFSU, Jul 10, 2014
    Last edited: Jul 10, 2014
    I have a 14-50 at the house that's always hot and can confirm that once it's done charging, it seems to only pull from shore power when you use the A/C or heat... otherwise, the center console, etc seems to pull from the battery... plugged in or not. I typically lose a few miles every 24hrs... even with the system "power save" option set for it to conserve power at the expense of starting up quicker...

    Also one other thing I've noticed is that if you schedule a charge to 90% (and I charge to 230 rated miles for example) then let the car sit for 24hrs and it hits the scheduled time again, it seems to know that it charged to 90% last time and that the loss it saw was vampire drain. It kicks on to charge, but seems to stop immediately not adding any additional miles... I'm fairly certain that if enough days went by, it would actually add some juice back into the battery, but like others here I'm not sure what that threshold of loss needs to be before it decides to truly charge again...
     
  10. golfski

    golfski Member

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    I am very curious about this vampire drain myself and how many miles you should expect to lose in 5.11. It seems that I pretty much lose 2 miles within 1-2 hours after I have parked or finished charging (charging or not, plugged in or not) and then its much slower after that. For instance, if I do a standard charge (90%) scheduled to start at 4:30 AM, I will be at 191 miles right when the charging stops at about 5:30/6AM. By the time I come out to go to work (7/7:30) I am already down to 189 miles, or 2 miles from whatever I finished charging at. If I actually don't leave and check a few hours later (11AM or so) I am down a total of 3 miles (188) and it seems to slowly lose a total of about 4-5 miles over 12 hours. Is this typical vampire drain? I am set in Energy Saver mode. I did once turn off the Energy Saver mode because I had been having trouble connecting to the car remotely and this seems to eat up even more. However, after I turned it back on - it seems that it is losing a little more than it used to. The weirdest thing is that it seems to take the first 2 miles off pretty quickly then slowly take more as time goes by.
     
  11. jamieb

    jamieb Member

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    This.

    I was recently out of the country for a week with my car plugged in at home set to charge to 90% at midnight. I checked the app daily and I could see that each day the ideal miles dropped from 269 to 265 to 261 etc., and that when it dropped into the 250s it charged up to 269 again the next cycle. I suspect there is a threshold % drop in SOC relative to what is set on the console and it then follows the charging schedule to bring it back up to the pre-set level.
     
  12. jomo25

    jomo25 P4398

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    Here are a couple graphs of my electricity usage over 2 week stretch when I went overseas. Left the car plugged into my GE Wattstation (208V/30A). I had the amps dialed down to 16A I think. The car was charged to my preset target level (I recall around 60%).

    As you can clearly see, the car doesn't draw shore power continuously. It sits and when the charge state goes down by a certain amount, it then draws to top up back to the target. First graph is kW draw (real time) the second is my daily kWh usage (total at midnight).
     

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  13. Muzzman1

    Muzzman1 Member

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    It's true. The car only draws on shore power when AC or battery preheat is used. You can tell she shore power is in use because you hear the contactors close and the hpwc shows the green lights rolling down.
    I'm overseas right now and when I check on my car it recharges every 2-3 days.
    Otherwise the contactors would be closed always.
     
  14. NigelM

    NigelM Recovering Member

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    The car only "tops off" every 24-48hrs under normal (i.e. comfortably warm) conditions. It will top off more frequently if power is drawn for heating or cooling.
     
  15. stevezzzz

    stevezzzz R;SigS;P85D;SigX

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    Wait, you have a car where a 90% charge is 269 miles!? Is that Rated miles? My S85 gives me 252 Rated miles after a 100% charge...
     
  16. rlang59

    rlang59 Member

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    It says ideal in the text you quoted:
    "...each day the ideal miles dropped from 269..."
     
  17. stevezzzz

    stevezzzz R;SigS;P85D;SigX

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    Doh! *blush*

    ...but why do you display Ideal miles? Do you get any useful information from it?
     
  18. jomo25

    jomo25 P4398

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    Won't ideal miles give you the best proximate on of actual battery capacity percentage wise?

    Like ideal mi/3 or something?

    Not that I use it either.
     
  19. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Not that I can tell.
     
  20. tezco

    tezco Sig P85

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    For a long time I used ideal miles to estimate % of remaining charge (divide ideal miles by 3). Mostly leave it on range now, though. Neither works very well during the winter for trips that start with a warm battery, park somewhere outside, and then return home late at night starting with a cold-soaked battery. Better have quite a bit more than 50% to make it home.
     

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